Daily markdown until sold

Statement

The Malavasi shop cuts the price of an item by $15\%$ each day until it is sold. How much will a $200\ \text{€}$ coat cost after $4$ days?

Solution

Each day $85\%$ remains: exponential decay $P=P_0\,(0{.}85)^{n}$. $P=200\,(0{.}85)^{4}=200\cdot 0{.}522006\approx\boxed{104{.}40\ \text{€}}.$